perf: fix N+1 query pattern across all modules + rack numbering

CRITICAL PERF BUG: Every hook did storage.list() (1 HTTP call fetching ALL
items with values, discarding values, returning only keys) then storage.get()
for EACH key (N individual HTTP calls re-fetching values one by one).

With 6 entries + contacts + tags, Registratura page fired ~40 sequential
HTTP requests on load, where 3 would suffice.

Fix: Replace list()+N*get() with single exportAll() call in ALL hooks:
- registratura/registry-service.ts (added exportAll to RegistryStorage interface)
- address-book/use-contacts.ts
- it-inventory/use-inventory.ts
- password-vault/use-vault.ts
- word-templates/use-templates.ts
- prompt-generator/use-prompt-generator.ts
- hot-desk/use-reservations.ts
- email-signature/use-saved-signatures.ts
- digital-signatures/use-signatures.ts
- ai-chat/use-chat.ts
- core/tagging/tag-service.ts (uses storage.export())

Additional fixes:
- registratura/use-registry.ts: addEntry uses optimistic local state update
  instead of double-refresh; closeEntry batches saves with Promise.all +
  single refresh
- server-rack.tsx: reversed slot rendering so U1 is at bottom (standard
  rack numbering, per user's physical rack)

Performance impact: ~90% reduction in HTTP requests on page load for all modules

src/modules/password-vault/hooks/use-vault.ts

@@ -1,31 +1,33 @@
-'use client';
+"use client";
 
-import { useState, useEffect, useCallback } from 'react';
-import { useStorage } from '@/core/storage';
-import { v4 as uuid } from 'uuid';
-import type { VaultEntry, VaultEntryCategory } from '../types';
+import { useState, useEffect, useCallback } from "react";
+import { useStorage } from "@/core/storage";
+import { v4 as uuid } from "uuid";
+import type { VaultEntry, VaultEntryCategory } from "../types";
 
-const PREFIX = 'vault:';
+const PREFIX = "vault:";
 
 export interface VaultFilters {
   search: string;
-  category: VaultEntryCategory | 'all';
+  category: VaultEntryCategory | "all";
 }
 
 export function useVault() {
-  const storage = useStorage('password-vault');
+  const storage = useStorage("password-vault");
   const [entries, setEntries] = useState<VaultEntry[]>([]);
   const [loading, setLoading] = useState(true);
-  const [filters, setFilters] = useState<VaultFilters>({ search: '', category: 'all' });
+  const [filters, setFilters] = useState<VaultFilters>({
+    search: "",
+    category: "all",
+  });
 
   const refresh = useCallback(async () => {
     setLoading(true);
-    const keys = await storage.list();
+    const all = await storage.exportAll();
     const results: VaultEntry[] = [];
-    for (const key of keys) {
-      if (key.startsWith(PREFIX)) {
-        const item = await storage.get<VaultEntry>(key);
-        if (item) results.push(item);
+    for (const [key, value] of Object.entries(all)) {
+      if (key.startsWith(PREFIX) && value) {
+        results.push(value as VaultEntry);
       }
     }
     results.sort((a, b) => a.label.localeCompare(b.label));
@@ -34,41 +36,81 @@ export function useVault() {
   }, [storage]);
 
   // eslint-disable-next-line react-hooks/set-state-in-effect
-  useEffect(() => { refresh(); }, [refresh]);
+  useEffect(() => {
+    refresh();
+  }, [refresh]);
 
-  const addEntry = useCallback(async (data: Omit<VaultEntry, 'id' | 'createdAt' | 'updatedAt'>) => {
-    const now = new Date().toISOString();
-    const entry: VaultEntry = { ...data, id: uuid(), createdAt: now, updatedAt: now };
-    await storage.set(`${PREFIX}${entry.id}`, entry);
-    await refresh();
-    return entry;
-  }, [storage, refresh]);
+  const addEntry = useCallback(
+    async (data: Omit<VaultEntry, "id" | "createdAt" | "updatedAt">) => {
+      const now = new Date().toISOString();
+      const entry: VaultEntry = {
+        ...data,
+        id: uuid(),
+        createdAt: now,
+        updatedAt: now,
+      };
+      await storage.set(`${PREFIX}${entry.id}`, entry);
+      await refresh();
+      return entry;
+    },
+    [storage, refresh],
+  );
 
-  const updateEntry = useCallback(async (id: string, updates: Partial<VaultEntry>) => {
-    const existing = entries.find((e) => e.id === id);
-    if (!existing) return;
-    const updated = { ...existing, ...updates, id: existing.id, createdAt: existing.createdAt, updatedAt: new Date().toISOString() };
-    await storage.set(`${PREFIX}${id}`, updated);
-    await refresh();
-  }, [storage, refresh, entries]);
+  const updateEntry = useCallback(
+    async (id: string, updates: Partial<VaultEntry>) => {
+      const existing = entries.find((e) => e.id === id);
+      if (!existing) return;
+      const updated = {
+        ...existing,
+        ...updates,
+        id: existing.id,
+        createdAt: existing.createdAt,
+        updatedAt: new Date().toISOString(),
+      };
+      await storage.set(`${PREFIX}${id}`, updated);
+      await refresh();
+    },
+    [storage, refresh, entries],
+  );
 
-  const removeEntry = useCallback(async (id: string) => {
-    await storage.delete(`${PREFIX}${id}`);
-    await refresh();
-  }, [storage, refresh]);
+  const removeEntry = useCallback(
+    async (id: string) => {
+      await storage.delete(`${PREFIX}${id}`);
+      await refresh();
+    },
+    [storage, refresh],
+  );
 
-  const updateFilter = useCallback(<K extends keyof VaultFilters>(key: K, value: VaultFilters[K]) => {
-    setFilters((prev) => ({ ...prev, [key]: value }));
-  }, []);
+  const updateFilter = useCallback(
+    <K extends keyof VaultFilters>(key: K, value: VaultFilters[K]) => {
+      setFilters((prev) => ({ ...prev, [key]: value }));
+    },
+    [],
+  );
 
   const filteredEntries = entries.filter((e) => {
-    if (filters.category !== 'all' && e.category !== filters.category) return false;
+    if (filters.category !== "all" && e.category !== filters.category)
+      return false;
     if (filters.search) {
       const q = filters.search.toLowerCase();
-      return e.label.toLowerCase().includes(q) || e.username.toLowerCase().includes(q) || e.url.toLowerCase().includes(q);
+      return (
+        e.label.toLowerCase().includes(q) ||
+        e.username.toLowerCase().includes(q) ||
+        e.url.toLowerCase().includes(q)
+      );
     }
     return true;
   });
 
-  return { entries: filteredEntries, allEntries: entries, loading, filters, updateFilter, addEntry, updateEntry, removeEntry, refresh };
+  return {
+    entries: filteredEntries,
+    allEntries: entries,
+    loading,
+    filters,
+    updateFilter,
+    addEntry,
+    updateEntry,
+    removeEntry,
+    refresh,
+  };
 }